Largest prime factor of 16^n + 1.

Terms

a(0) =2a(1) =17a(2) =257a(3) =241a(4) =65537a(5) =61681a(6) =673a(7) =15790321a(8) =6700417a(9) =38737a(10) =4278255361a(11) =2931542417a(12) =22253377a(13) =308761441a(14) =54410972897a(15) =4562284561a(18) =487824887233a(21) =88959882481